Merge tag 'xfs-4.12-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

[karo-tx-linux.git] / fs / btrfs / extent_io.c

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d8da3edf2ac39ebcc0bde0ede7da74f0f81ad9ea..d3619e01000551c42bf65bd6983801a0b04423e5 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2458,7 +2458,7 @@ void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
        if (!uptodate) {
                ClearPageUptodate(page);
                SetPageError(page);
-               ret = ret < 0 ? ret : -EIO;
+               ret = err < 0 ? err : -EIO;
                mapping_set_error(page->mapping, ret);
        }
 }
@@ -4377,6 +4377,123 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode,
        return NULL;
 }
 
+/*
+ * To cache previous fiemap extent
+ *
+ * Will be used for merging fiemap extent
+ */
+struct fiemap_cache {
+       u64 offset;
+       u64 phys;
+       u64 len;
+       u32 flags;
+       bool cached;
+};
+
+/*
+ * Helper to submit fiemap extent.
+ *
+ * Will try to merge current fiemap extent specified by @offset, @phys,
+ * @len and @flags with cached one.
+ * And only when we fails to merge, cached one will be submitted as
+ * fiemap extent.
+ *
+ * Return value is the same as fiemap_fill_next_extent().
+ */
+static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
+                               struct fiemap_cache *cache,
+                               u64 offset, u64 phys, u64 len, u32 flags)
+{
+       int ret = 0;
+
+       if (!cache->cached)
+               goto assign;
+
+       /*
+        * Sanity check, extent_fiemap() should have ensured that new
+        * fiemap extent won't overlap with cahced one.
+        * Not recoverable.
+        *
+        * NOTE: Physical address can overlap, due to compression
+        */
+       if (cache->offset + cache->len > offset) {
+               WARN_ON(1);
+               return -EINVAL;
+       }
+
+       /*
+        * Only merges fiemap extents if
+        * 1) Their logical addresses are continuous
+        *
+        * 2) Their physical addresses are continuous
+        *    So truly compressed (physical size smaller than logical size)
+        *    extents won't get merged with each other
+        *
+        * 3) Share same flags except FIEMAP_EXTENT_LAST
+        *    So regular extent won't get merged with prealloc extent
+        */
+       if (cache->offset + cache->len  == offset &&
+           cache->phys + cache->len == phys  &&
+           (cache->flags & ~FIEMAP_EXTENT_LAST) ==
+                       (flags & ~FIEMAP_EXTENT_LAST)) {
+               cache->len += len;
+               cache->flags |= flags;
+               goto try_submit_last;
+       }
+
+       /* Not mergeable, need to submit cached one */
+       ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
+                                     cache->len, cache->flags);
+       cache->cached = false;
+       if (ret)
+               return ret;
+assign:
+       cache->cached = true;
+       cache->offset = offset;
+       cache->phys = phys;
+       cache->len = len;
+       cache->flags = flags;
+try_submit_last:
+       if (cache->flags & FIEMAP_EXTENT_LAST) {
+               ret = fiemap_fill_next_extent(fieinfo, cache->offset,
+                               cache->phys, cache->len, cache->flags);
+               cache->cached = false;
+       }
+       return ret;
+}
+
+/*
+ * Sanity check for fiemap cache
+ *
+ * All fiemap cache should be submitted by emit_fiemap_extent()
+ * Iteration should be terminated either by last fiemap extent or
+ * fieinfo->fi_extents_max.
+ * So no cached fiemap should exist.
+ */
+static int check_fiemap_cache(struct btrfs_fs_info *fs_info,
+                              struct fiemap_extent_info *fieinfo,
+                              struct fiemap_cache *cache)
+{
+       int ret;
+
+       if (!cache->cached)
+               return 0;
+
+       /* Small and recoverbale problem, only to info developer */
+#ifdef CONFIG_BTRFS_DEBUG
+       WARN_ON(1);
+#endif
+       btrfs_warn(fs_info,
+                  "unhandled fiemap cache detected: offset=%llu phys=%llu len=%llu flags=0x%x",
+                  cache->offset, cache->phys, cache->len, cache->flags);
+       ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
+                                     cache->len, cache->flags);
+       cache->cached = false;
+       if (ret > 0)
+               ret = 0;
+       return ret;
+}
+
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                __u64 start, __u64 len, get_extent_t *get_extent)
 {
@@ -4394,6 +4511,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
        struct extent_state *cached_state = NULL;
        struct btrfs_path *path;
        struct btrfs_root *root = BTRFS_I(inode)->root;
+       struct fiemap_cache cache = { 0 };
        int end = 0;
        u64 em_start = 0;
        u64 em_len = 0;
@@ -4573,8 +4691,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                        flags |= FIEMAP_EXTENT_LAST;
                        end = 1;
                }
-               ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
-                                             em_len, flags);
+               ret = emit_fiemap_extent(fieinfo, &cache, em_start, disko,
+                                          em_len, flags);
                if (ret) {
                        if (ret == 1)
                                ret = 0;
@@ -4582,6 +4700,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                }
        }
 out_free:
+       if (!ret)
+               ret = check_fiemap_cache(root->fs_info, fieinfo, &cache);
        free_extent_map(em);
 out:
        btrfs_free_path(path);